Control mechanism for electrically operable bed

ABSTRACT

An electrically operable bed having a horizontal frame and an articulated spring supported by the frame which has pivotably mounted head, knee, and foot sections. Actuating means are mounted on the frame for effecting desired movement of the spring, including head section drive means and knee section drive means, the drive means being operated by a reversible electric motor via transmission means. A limiting means is associated with at least one of the drive means for limiting the degree of movement of the spring section movable thereby to a predetermined degree of movement.

United States Patent Damico [111 3,840,910 [451 Oct.15,1974

CONTROL MECHANISM FOR ELECTRICALLY OPERABLE BED [75] Inventor: Frank W. Damico, Stevens Point,

Wis.

[73] Assignee: Joeens Furniture Company, Stevens Point, Wis.

[22] Filed: Mar. 16, 1973 [21] Appl. No.: 341,869

152] US. Cl. 5/66, 5/68 [51] Int. Cl. A47c 3/32 [58] Field of Search S/66-69; 200/5 [56] References Cited UNITED STATES PATENTS 2,913,300 11/1959 Darnell et al. 5/68 3,198,891 8/1965 Burst et al. 5/68 X 3,710,404 1/1973 Peterson 5/68 Primary ExaminerCasmir A. Nunberg Attorney, Agent, or Firm-Price, Heneveld, l-luizenga & Cooper [57] ABSTRACT An electrically operable bed having a horizontal frame and an articulated spring supported by the frame which has pivotably mounted head, knee, and foot sections. Actuating means are mounted on the frame for effecting desired movement of the spring, including head section drive means and knee section drive means, the drive means being operated by a reversible electric motor via transmission means. A limiting means is associated with at least one of the drive means for limiting the degree of movement of the spring section movable thereby to a predetermined degree of movement.

12 Claims, 10 Drawing Figures PATENTED 0m 1 51974 SHEET 1 OF 5 PATENTED 3,840,910

SHEET 2!]? 5 PATENIEU um 1 51914 slim 50$ 5 CONTROL MECHANISM FOR ELECTRICALLY OPERABLE BED BACKGROUND OF THE INVENTION This invention relates to hospital beds, and more particularly to those selectively operable electrically to raise and lower pivotally swingable head and knee sections of an articulated frame of such beds.

A variety of electrically operable beds are currently used in hospitals which have controls accessible to the patient for raising and lowering the head and knee sections of the articulated frames of such beds. For example, such an electrically operable bed is disclosed in US. Pat. No. 3,581,319 issued June l, 1971 to J. F. Stanley et al., and entitled ELECTRICALLY OPERA- BLE BED and in US. Pat. No. 3,710,404 issued Jan. 16, 1973, to W. J. Peterson and entitled ELECTRIC HOSPITAL BED. Although many of these beds are perfectly satisfactory from a mechanical point of view, in the case of certain injuries, it is not medically desirable to permit the patient to have too great a latitude in the adjustability of his bed because of the chance of aggrevation of his injuries by too great an adjustment of his bed and pressures which may be exerted on parts of the body when the bed is adjusted to too high a degree. For example, in the case of certain knee injuries, it has been found that raising the knee section of the bed more than about 20 can aggrevate such injury and exert a pressure behind the knee which may adversely effect the blood flow. Thus, in the case of such an injury, it is desirable to have a bed which the patient cannot raise the knee section thereof more than about 20. However, since in the case of patients with other injuries, it may be desirable or even necessary to raise the knee section more than 20, it would be impractical to construct a bed the knee section of which could not be raised beyond 20.

Thus, there is a need for an electrically operable hospital bed which limits the patients ability to adjust the spring sections thereof beyond a certain degree but which also permits the patients controls to be overridden when a greater adjustment is desired or necessary.

SUMMARY OF THE INVENTION According to the present'invention, there is provided an electrically operable bed having a horizontal frame and an articulated spring supported by the frame which has pivotably mounted head, knee, and foot sections. Actuating means are mounted on the frame for effecting desired movement of the spring, including head section drive means for moving the head section relative to the frame, and knee section drive means for moving the knee section relative to the frame. The drive means are operated by a reversible electric motor mounted on the frame via transmission means-A limiting means is associated with at least one of the drive means, preferably the knee section drive means, for limiting the degree of movement of the spring section movable thereby to a predetermined degree of movement. At least one actuator push rod is provided for selectively actuating the motor in opposite directions to selectively operate the drive means to raise and lower the spring section movable thereby, the actuator push rod being movable between a rising, a neutral, and a lowering position.

The drive means preferably includes a rotatable screw member and a nut member threadably engaged therewith, the screw member being rotatable by the electric motor via the transmission means to produce actual movement of the nut member in either axial direction. The nut member is connected to the spring section by linkage means so that axial movement of the nut member in one direction raises that spring section and axial movement of the nut member in the opposite direction lowers-that spring section. The limiting means is actuatable by the drive means to urge the actuator rod from the raising position toward the neutral position when the spring section movable by that drive means is raised to a predetermined position. Preferably, the limiting means comprises a cam follower stud on the nut member and cam means mounted on the bed frame positioned so that when the nut member is moved axially to an axial position where the spring section reaches the predetermined raised position, the stud member will move the cam means to urge the actuator rod from the raising position toward the neutral position. Preferably, a pair of actuator push rods are provided for each drive means which has limiting means associated therewith, with one of the actuator push rods being positioned on the bed so as to be easily operable by an occupant of the bed and the other actuator push rod being positioned on the bed remote from the occupant for operation by a nurse or other attendant. In such case, the remote actuator push rod is operable to override the limiting means so that the particular bed section can be raised beyond the predetermined raised position to which the bed occupant actuator rod is limited. I

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a plan view, with parts broken away, of a bed emobdying features of the present invention;

FIG. 2 is a plan view of the bed of FIG. 1 showing a single drive means with limiting means according to the present invention, with other elements of the bed having been removed;

FIG. 3 is an enlarged plan view of a portion of the bed of FIG. 2 illustrating the details of the preferred limiting means of the bed of the present invention;

FIG. 4 is a side, elevational view of the bed portion of FIG. 3 taken along the line IVIV of FIG. 3;

FIG. 5 is a perspective view of a bell plate used in the preferred limiting means of the present invention;

FIG. 6 is a perspective view of a cam plate used in the preferred limiting means of the present invention;

FIGS. 7-9 are enlarged plan views of the bed portion shown in FIG. 3 showing the limiting means in various positions of adjustment; and

FIG. 10 is a schematic side-elevational view of the bed illustrating the various sections of the bed in different adjusted positions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in more detail, FIGS. 1, 2, and 10 show an electrically operable bed embodying the features of the present invention. The bed comprises a main frame 11 which is supported at each end in a well-known manner by means of four outer legs 12 secured thereto. The main frame 11 supports a normally horizontally'dispos'ed, articulated spring which comprises an intermediate or seat section 114 rigidly secured to the frame, a. head section 15 pivotally connected to the intermediate section at 16, a knee section 17 pivoted to the seat section 14 at 18, and a foot section 19 pivotally connected at 21 to the knee section 17. The frame 11 includes side rails 22, and a plurality of rigid transverse members including outer and inner gear box plates 23 and 24 and a bearing frame plate 25.

Head section drive means are provided for raising and lowering the head section 15 of the spring about its pivot 16 relative to the frame 11 which includes a head screw 33 mounted in suitable thrust bearings carried by the inner gear box plate 24 and the frame plate 25. A nut 34 threadably engages the screw 33 and is connected to the rear ends of the forwardly extending links 35. The forward ends of links 35 are pivotally connected to crank arm means 36 to swing the head section 15 up or down about its pivot 16 depending upon the direction of rotation of the head screw 33 and the resultant axial movement of nut 34.

Knee section drive means of similar construction are also provided for raising and lowering the knee section 17 about its pivot 18 relative to the frame 11. The knee section drive means includes a knee screw 38 mounted in a similar manner to the screw 33, a nut 39 threadably engaging screw 38 similarly to nut 34 and screw 33, and forwardly extending links 40 connected at their rear ends to nut 39. The forward ends of links 30 are pivotally connected to crank arm means 41 secured to a transverse crank shaft 42 depending from the inner end portion of the knee section 17. Rotation of the knee screw 38 thus will be transmitted by means of nut 39, links 40, crank arm means 41 and crank shaft 42 to the knee section 17 to swing the same up or down about its pivot 18 depending on the direction of rotation of the screw 38 (see FIG.

The drive screws 33 and 38 are adapted to be selectively actuated by a reversibly operable electric motor 43 through the agency of transmission means mounted between the plates 23 and 24. The transmission means 44 are conventional andcomprise a seriesof sprocket wheels, chains, and gears such as disclosed in the above-mentioned US. Pat. Nos. 3,581,319 and 3,710,404. Thus, motor 43 can be selectively actuated to rotate either screw 33 or screw 38 to raise or lower head section and knee section 17, respectively.

' As disclosed in US. Pat. No. 3,58 l ,319 and US. Pat. No. 3,710,404, the operation of reversible motor 43 is controlled by microswitches which are sele'ctively actuated by longitudinal movement of a switch bar 50. Lougitudinal movement of switch bar 50 is produced in a conventional manner by pivoting movement of rigid control straps or bars 51 or 52, pivoting of control bar 51 causing motor 43 to be energized to raise or lower head section 15 and pivoting of control bar 52 causing motor 43 to be energized to raise or lower knee section 17.

Control bar 51 is pivoted by means of either of a pair of actuator push rods 53 and 54, and control bar 52 is pivoted by means of either of a pair of actuator push rods 55 and 56. Actuator push rods 53 and 55 extend from their respective control bars to the foot of the bed where they are secured to and actuable by means of bell crank handles 57 and 58, respectively, which are actuable by a nurse or other attendant. (A third bell, crank handle 63 can be included to operate a vertical bed raising mechanism [not shown] if such is included on the bed.)

Actuator push rods 54 and 56 extend to intermediate section 14 where they are linked to the transverse control rods 59 and 60, respectively, which in turn are connected to the control levers 61 and 62, respectively, provided on both sides of the bed and which are accessible to the bed occupant. Thus, a pivoting movement of either of levers 61 will rotate control rod 59 to move actuator push rod 54 for actuation of motor 43 to raise or lower head section 15. Similarly, pivoting movement of either of levers 62 will rotate control rod 60 to cause movement of actuator push rod 56 to actuate motor 43 to raise or lower knee section 17. As will be appreciated, as knee section 17 is raised, the end of foot section 19 which is hinged thereto will alsobe raised with the other end of foot section 19 being supported by pivoting arms 110 and 111 (see FIG. 10).

A novel limiting means is associated with the knee section drive means for limiting the degree of raising movement of knee section 17 by the bed occupant via control levers 62. This limiting means is most clearly shown in FlGxZ in which other elements of the bed have been removed to more clearly show the elements of the limiting means. Further structural detail of the limiting means is shown in FIGS. 3-9 to which reference will also be made. The limiting means includes a stop plate 80 which is moved into the path of the actuator push rod 56 (which is the rod actuated by the patient) in response to the knee section 17 being pivoted to a predetermined position. Thus, stop plate 80 prohibitsfurther raising of the knee section by the patient.

As shown, the limiting means includes a cam means comprising a cam plate 70, the stop plate 80, and a cam actuator member 90. One end 71 of cam plate is pivotally mounted to frame plate 25 by means of a shoulder bolt or the like through aperture 72 so that the opposite end 73 can be swung through an arc. End 73 has an elongated aperture 74 for mounting end 73 to frame plate 24 on a shoulder bolt member or the like 75 so that end 73 can be swung through a limited arc. Cam plate 70 also has an aperture 76 for receipt of depending tongue 81 of stop plate 80. Stop plate is mounted on top of end 73of cam plate 70' by means of shoulder bolt member 75 passing through aperture 82 so that stop plate 80 is pivotable on shoulder bolt member 75. Depending ton'gue8l is positioned through aperture 76 so that when end 73 of cam plate 50 is swung through a clockwise arc, stop plate 80 will be pivoted through a counterclockwise 'arc and vice versa. Extending up from stop plate 80 is a stop flange 83 for engagement with the end of actuator push rod 56 as will be expalined more fully hereinafter.

Cam plate 70 includes a cam ramp portion 77 for engagement by cam actuator 90. Cam actuator is rigidly mountedadjacent nut member 39. Thus, as nut 39 is moved axially toward the foot of the bed, cam actuator 90 will contact cam ramp portion 77 of cam plate 70 to pivot end 73 in a counterclockwise arc to produce clockwise pivoting of stop plate 80.

The end of actuator push rod 56 is secured. to control bar 52 by means of a collar member which is affixed to one end of control bar 52. The end of actuator push rod 56 has a stepped-down diameter which passes through an aperture in collar 100. The stepped-down diameter of the end of push rod 56 provides a shoulder portion which abuts the inward side of collar 100 so that as push rod 56 is pushed toward the foot of the bed, control bar 52 will be pivoted counterclockwise. The stepped-down diameter portion of push rod 56 passes through and beyond the aperture in collar 100 for receipt of a coil spring 101 which is secured on the end of push rod 56 by means of a suitable washer 102 or the like. The diameter of coil spring 101 is greater than the diameter of the aperture through collar 100 and the rigidity of coil spring 101 is great enough so that as push rod 56 is moved toward the head of the bed, control bar 52 will be pivoted in a clockwise direction. The purpose of coil spring 101 is to permit the limiting means to be overridden by movement of actuator push rod 55 as will be explained more fully hereinafter.

OPERATION The operation of the limiting means to limit the bed occupants ability to raise knee section 17 beyond a predetermined raised position will now be explained. FIG. 3 depicts actuator push rod 56 in the neutral position, i.e., with motor 43 not being energized. When the bed occupant desires to raise knee section 17, he pulls one of the control levers 62 toward the head of the bed which moves push rod 56 toward the foot of the bed to pivot control bar 52 in a counterclockwise direction which in turn moves switch bar 50 toward the head of the bed to energize motor 43 in the raising direction. Energizing of motor 43 causes the screw 38 to rotate to move nut 39 axially in the direction of the foot of the bed to raise knee section'l7 via links 40 and crank arm means 41. As nut member 39 moves axially toward the foot of the bed, cam actuator 90 will contact cam ramp portion 77 of cam plate 70 to pivot the end 73 in a counterclockwise direction. This in turn will pivot stop plate 80 in a clockwise direction so that stop flange 83 moves toward the end of push rod 56 (FIG. 7). As nut 39 continues toward the foot of the bed, cam actuator 90 will reach the end of cam ramp portion 77, at which point the end 73 of cam plate 70 will be swung to the end of the counterclockwise are permitted by aperture 74 and stop flange 83 of stop plate 80 will have contacted the end of push rod 56 and urged it back toward the neutral position (FIG. 8). Moving push rod 56 toward the neutral position will de-energize motor 43 via control bar 52 and switch bar 50 to stop'the raising movement of knee section 17. It is not necessary to move push rod 56 completely back to the neutral position since motor 43 will be de-energized by only a small movement of push rod 56 toward the neutral position. As long as ca'm actuator 90 remains in contact with the side of cam plate 70, as shown in FIG. 8, stop flange 83 will prevent push rod 56 from being returned to the raising position, and thus, the bed occupant will not be able to raise knee section 17 any further.

In the event it is deemed desirable for medical reasons, etc, to raise knee section 17 beyond this predetermined raised position, the limiting means may be overriden by energizing motor 43 via actuator push rod 55 from the foot of the bed. As actuator push rod 55 is moved toward the head of the bed by bell crank handle 58, control rod 52 will again be pivoted in a counterclockwise direction to move switch bar 50 toward the head of the bed to re-energize motor 43 to continue the raising movement of knee section 17. Because of the stepped-down diameter on the end of actuator push rod 56, collar 100 will be moved toward the end of push rod 56 against the biasing force of spring 1101 when actuator handle 58 and push rod 55 are employed to pivot control rod 52 (FIG. 9). Thus, even though push rod 56 still cannot be returned to the raised position because of stop flange 83, stop flange 83 does not prevent the pivoting of control bar 52 by means of actuator 58. However, stop flange83 does offer resistance to movement of rod 56 and thus, the attendant at the end of the bed as he or she actuates handle 58 very clearly will sense when the knee section is raised to 20 because as that point is reached, an extra amount of force on handle 58 is required to overcome the force of spring 101. Accordingly, the mechanism does indicate to the attendant when the 20 raised position is reached.

In order to lower knee section 17 to the horizontal position, either push rod 55 is pulled toward the foot of the bed by handle 58 or push rod 56 is pulled toward the head of the bed by handle 62 to pivot control bar 52 in a clockwise direction to push switch bar 50 toward the foot of the bed to actuate motor 43 in reverse. As screw 38 is rotated in reverse, nut 39-will travel axially toward the-head of the bed to lower knee section 17. Cam actuator 90 will travel with nut member 39 back to the position shown in FIG. 3. Although cam plate will then be left in the extreme of its counterclockwise arc and stop flange 82 of stop plate adjacent the end of push rod 56 when push rod 56 is returned toward the neutral position, movement of push rod 56 by the bed occupant toward the foot of the bed will cause stop plate 80 and cam plate 70 to return to the position of FIG. 3 since cam actuator will not be adjacent cam plate 70 to prevent clockwise pivoting thereof. Of course, conventional spring means can be employed to bias cam plate 70 and stop plate 80 back to the position of FIG. 3 as soon as cam actuator 90 disengages from contact with cam plate 70, but this is not necessary and will not affect the efflciency of the operation of the limiting means.

Although the limiting means of the present invention has been described and illustrated in connection with the knee section, it will be obvious to those skilled in the art thatthe limiting means can be employed in conjunction with the drive means for the head section in similar fashion. Further, the limiting means can be employed to limit the degree of raising of a particular spring section to any predetermined limit and is dependant only upon the location of cam-ramp 77 on cam plate 70 relative to the point at which it will be engaged by cam actuator member 90 to actuate the limiting means. Thus, although it will generally be preferred to design the limiting means to limit raising of the knee sectionby the bed occupant no more than about 20, as discussed above, this is merely a matter of choice. Finally, it will be obvious to those skilled in the art that a variety of modifications can be made in the limiting means of the present invention without departing from the spirit thereof. For example, the limiting means can be employed to restrict lowering the bed section as well as to restrict the raising thereof. In addition, the particular configuration of the bell crank plate, the cam plate, and the cam follower stud can be changed or rearranged to provide similar results. Thus, the scope of the present invention is deemed to be limited only by the following appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: v

1. In an electrically operable bed having a horizontal frame; an articulated spring supported by said frame having at least one adjustable section; electrically operable actuating means mounted on said frame for effecting desired movements of said spring section, including drive means for moving said section relative to said frame; a reversible electric motor mounted on said frame, and transmission means mounted on said frame for selectively operating said drive means by said motor; the improvement which comprises: limiting means operably associated with said drive means for limiting the degree of movement of the spring section movable by said drive means to a predetermined degree of movement, said predetermined degree of movement being less than the full raising movement obtainable by said electrically operable actuating means; and wherein said electrically operable actuating means includes a first control means accessible to an occupant of said bed and being operably connected to said limiting means whereby said first control means is operable by an occupant of said bed to selectively operate said drive means only to the extent permitted by said limiting means; and a second control means positioned on said bed remote from said occupant to selectively operate said drive means to the full raising movement obtainable independently of said limiting means.

2. An electrical operable bed according to claim 1 wherein said first control means includes a first actuator push rod for selectively actuating said motor'in opposite directions to selectively operate said drive means to raise and lower said spring section movable thereby, said first actuator rod being movable between a raising, a neutral, and a lowering position; said limiting means being actuatable by said drive means to urge said first actuator rod toward the neutral position and/or to re strain said first actuator rod from being positioned in the raising position when said spring section movable by said drive means is raised to said predetermined position.

3. An electrical operable bed according to claim 2 wherein said second control means includes a second actuator push rod, and said second rod is operable to override said limiting means whereby said second rod can be retained in the raising position after said predetermined raised position is reached to raise said section movable by said drive means beyond said predetermined raised position.

4. An electrically operable bed according to claim 1 wherein said first control means includes a first actuator for selectively actuating said motor in opposite directions to selectively operate said drive means to raise and lower said spring section movable thereby, said first actuator being movable between araising, a neutral, and a lowering position; said limiting means being actuatable by said drive means to urge said first actuator toward the neutral position and/or to restrain said first actuator from being positioned in the raising position when said spring section movable by said drive means is raised to a predetermined position.

5. An electrically operable bed according to claim 4 wherein said second control means includes a second actuator and said second actuator is operable to override said limiting means whereby said second actuator can be retained in the raising position after said perdetermined raised position is reached to raise said section movable by said drive means beyond said predetermined raised position.

6. An electrically operable bed according to claim 2 wherein said drive means includes a rotatable screw member and a nut member threadably engaged therewith, said screw member being rotatable by said motor via said transmission means to produce axial movement of said nut member in either axial direction and said nut member being connected to said spring section movable by said drive means by linkage means so that axial movement of said nut member in one direction raises said spring section movable by said drive means and axial movement of said nut member in the opposite direction lowers said spring section movable by said drive means; said limiting means comprising a cam actuator adjacent said nut means; and cam means on said frame positioned so that when said nut means is axially moved to an axial position where said spring section movable by said drive means is at said predetermined raised position, said cam actuator will move said cam means to urge said first actuator push rod toward the neutral position and/or to restrain said first actuator push rod from being positioned in the raising position.

7. An electrically operable bed according to claim 6 wherein said cam means comprises a cam plate and a stop plate; said cam plate and said stop plate each being pivotably mounted on said frame and positioned with respect to' each other so that pivoting of either orie of said plates causes the other of said plates to pivot; said cam plate having a cam ramp portion engageable by said cam actuator when said nut means is at said axial position to pivot said cam plate to cause said stop plate to pivot to urge said first actuator push rod toward the neutral position and/or to restrain said first actuator push rod from being positioned in the raising position.

8. An electrically operable bed according to claim 3 wherein said drive means includes a rotatable screw member and a nut member threadably engaged therewith, said screw member being rotatable by said motor via said transmission means to produce axial movement of said nut member in either axial direction and said nut member being connected to said spring section movable by said drive means by linkage means so that axial movement of said nut member in one direction raises said spring section movable by said drive means and axial movement of said nut member in the opposite direction lowers said-spring section movable by said drive means; said limiting means comprising a cam a'ctuator adjacent said nut means; and cam means on said frame positioned so that when said nut means is axially moved to an axial position where said spring section movable by said drive means is at said predetermined raised position, said cam actuator will move said cam means to urge said first actuator push rod toward the neutral position and/or to restrain said first actuator push rod from being positioned in the raising position.

9. An electrically operable bed according to claim 8 wherein said cam means comprises a cam plate and a stop plate; said cam plate and said stop plate each being pivotally mounted on said frame and positioned with respect to each other so that pivoting of either one of said plates causes the other of said plates to pivot; said cam plate having'a cam ramp portion engageable by said cam actuator when said nut means is at said axial position to pivot said cam plate to cause said stop plate to pivot to urge said first actuator push rod toward the neutral position and/or to restrain said first actuator push rod from being positioned in the raising position.

10. An electrically operable bed according to claim 9 wherein said first and second actuator push rods are coupled to a common pivotally mounted rigid control bar, the pivotal movement of said control bar by either of said actuator push rods causing actuation of said motor, said first rod being resiliently coupled to said control bar so that said control bar can be pivoted by said 12. An electrically operable bed according to claim 1 wherein said adjustable section is the knee section and said drive means is the knee section drive means.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,840,910 Dated October 15, 1974 Inventor) Frank M. Damico It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On Cover Page;

After "Inventor:", "Frank W. Damico" should be --Frank M. Damico--;

Column 1, Line 66;

"rising" should be --raising--;

Column 6, line 28;

"82" should be --83-- Signed and sea led this 8th day of April 1975.

(SEAL) Attest:

C. EARSFALL DART RUTH C. I'=IASON Commissioner of Patents attesting Officer and Trademarks FORM PC4050 (10-69) USCOMM-DC 6037 fl-POD ".5. GOVIINMINT IIIIIYIIIG OFFICE "I, O-ll-JS, 

1. In an electrically operable bed having a horizontal frame; an articulated spring supported by said frame having at least one adjustable section; electrically operable actuating means mounted on said frame for effecting desired movements of said spring section, including drive means for moving said section relative to said frame; a reversible electric motor mounted on said frame, and transmission means mounted on said frame for selectively operating said drive means by said motor; the improvement which comprises: limiting means operably associated with said drive means for limiting the degree of movement of the spring section movable by said drive means to a predetermined degree of movement, said predetermined degree of movement being less than the full raising movement obtainable by said electrically operable actuating means; and wherein said electrically operable actuating means includes a first control means accessible to an occupant of said bed and being operably connected to said limiting means whereby said first control means is operable by an occupant of said bed to selectively operate said drive means only to the extent permitted by said limiting means; and a second control means positioned on said bed remote from said occupant to selectively operate said drive means to the full raising movement obtainable independently of said limiting means.
 2. An electrical operable bed according to claim 1 wherein said first control means includes a first actuator push rod for selectively actuating said motor in opposite directions to selectively operate said drive means to raise and lower said spring section movable thereby, said first actuator rod being movable between a raising, a neutral, and a lowering position; said limiting means being actuatable by said drive means to urge said first actuator rod toward the neutral position and/or to restrain said first actuator rod from being positioned in the raising position when said spring section movable by said drive means is raised to said predetermined position.
 3. An electrical operable bed according to claim 2 wherein said second control means includes a second actuator push rod, and said second rod is operable to override said limiting means whereby said second rod can be retained in the raising position after said predetermined raised position is reached to raisE said section movable by said drive means beyond said predetermined raised position.
 4. An electrically operable bed according to claim 1 wherein said first control means includes a first actuator for selectively actuating said motor in opposite directions to selectively operate said drive means to raise and lower said spring section movable thereby, said first actuator being movable between a raising, a neutral, and a lowering position; said limiting means being actuatable by said drive means to urge said first actuator toward the neutral position and/or to restrain said first actuator from being positioned in the raising position when said spring section movable by said drive means is raised to a predetermined position.
 5. An electrically operable bed according to claim 4 wherein said second control means includes a second actuator and said second actuator is operable to override said limiting means whereby said second actuator can be retained in the raising position after said perdetermined raised position is reached to raise said section movable by said drive means beyond said predetermined raised position.
 6. An electrically operable bed according to claim 2 wherein said drive means includes a rotatable screw member and a nut member threadably engaged therewith, said screw member being rotatable by said motor via said transmission means to produce axial movement of said nut member in either axial direction and said nut member being connected to said spring section movable by said drive means by linkage means so that axial movement of said nut member in one direction raises said spring section movable by said drive means and axial movement of said nut member in the opposite direction lowers said spring section movable by said drive means; said limiting means comprising a cam actuator adjacent said nut means; and cam means on said frame positioned so that when said nut means is axially moved to an axial position where said spring section movable by said drive means is at said predetermined raised position, said cam actuator will move said cam means to urge said first actuator push rod toward the neutral position and/or to restrain said first actuator push rod from being positioned in the raising position.
 7. An electrically operable bed according to claim 6 wherein said cam means comprises a cam plate and a stop plate; said cam plate and said stop plate each being pivotably mounted on said frame and positioned with respect to each other so that pivoting of either one of said plates causes the other of said plates to pivot; said cam plate having a cam ramp portion engageable by said cam actuator when said nut means is at said axial position to pivot said cam plate to cause said stop plate to pivot to urge said first actuator push rod toward the neutral position and/or to restrain said first actuator push rod from being positioned in the raising position.
 8. An electrically operable bed according to claim 3 wherein said drive means includes a rotatable screw member and a nut member threadably engaged therewith, said screw member being rotatable by said motor via said transmission means to produce axial movement of said nut member in either axial direction and said nut member being connected to said spring section movable by said drive means by linkage means so that axial movement of said nut member in one direction raises said spring section movable by said drive means and axial movement of said nut member in the opposite direction lowers said spring section movable by said drive means; said limiting means comprising a cam actuator adjacent said nut means; and cam means on said frame positioned so that when said nut means is axially moved to an axial position where said spring section movable by said drive means is at said predetermined raised position, said cam actuator will move said cam means to urge said first actuator push rod toward the neutral position and/or to restrain said first actuator push rod from being positioned in the raising position.
 9. An electrically operable bed according to claim 8 wherein said cam means comprises a cam plate and a stop plate; said cam plate and said stop plate each being pivotally mounted on said frame and positioned with respect to each other so that pivoting of either one of said plates causes the other of said plates to pivot; said cam plate having a cam ramp portion engageable by said cam actuator when said nut means is at said axial position to pivot said cam plate to cause said stop plate to pivot to urge said first actuator push rod toward the neutral position and/or to restrain said first actuator push rod from being positioned in the raising position.
 10. An electrically operable bed according to claim 9 wherein said first and second actuator push rods are coupled to a common pivotally mounted rigid control bar, the pivotal movement of said control bar by either of said actuator push rods causing actuation of said motor, said first rod being resiliently coupled to said control bar so that said control bar can be pivoted by said second rod by being moved to the raising position of said second rod without movement of said first rod whereby said second rod is operable for said overriding of said limiting means.
 11. An electrically operable bed according to claim 10 wherein said adjustable section is the knee section and said drive means is the knee section drive means.
 12. An electrically operable bed according to claim 1 wherein said adjustable section is the knee section and said drive means is the knee section drive means. 